A tornado is a rapidly rotating column of air extending from the base of a thunderstorm that comes in contact with the ground.
The biggest tornado ever recorded in history: The biggest tornado ever recorded was the Tri-State Tornado. This devastating column of air took place through parts of Missouri, Illinois, and Indiana on the day of March 18, 1925. It is projected to have been a F5. We can't confirm this though because tornados were not ranked during that period of time. It had a path length of 219 miles(352 km), a duration of about 3.5 hours, and a record speed of 73 mph(117 km/h). It is also recorded to have taken the lives of 650 individuals.
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Although tornadoes occur in many parts of the world, they are found most frequently in the United States.....
A tornado is a violently rotating column of air extending from a thunderstorm to the ground.
Tornadoes cause an average of 70 fatalities and 1,500 injuries in the U.S. each year..
The strongest tornadoes have rotating winds of more than 250 mph.
Tornadoes can be one mile wide and stay on the ground over 50 miles.
Tornadoes may appear nearly transparent until dust and debris are picked up or a cloud forms within the funnel. The average tornado moves from southwest to northeast, but tornadoes have been known to move in any direction.
The average forward speed is 30 mph but may vary from nearly stationary to 70 mph.
Waterspouts are tornadoes which form over warm water. They can move onshore and cause damage to coastal areas
How do they form?
Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere.
Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical.
An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
Anatomy of a Tornado
1. Warm, moist air at the surface rises rapidly, creating an updraft. 2. Falling rain evaporates, cooling the air around it. 3. The wall cloud rotates as it's hit with winds from opposite directions. 4. As the rotation intensifies, a visible funnel drops out of the clouds. 5. A prominent overshooting top forms when the updraft is very strong. 6. Powerful updrafts give hail time to form. 7. A dust shroud is kicked up by the tornado's strong winds at ground level. 8. Central downdrafts appear in some tornadoes.
Fujita Tornado Damage Scale
F0: Light Damage (<73 mph); Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged. (1-10 min)
F1: Moderate Damage (73-112 mph); Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off road. (1-10 min)
F2: Considerable Damage (113-157 mph); Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground. (20+ min)
F3: Severe Damage (158- 206 mph); Roofs and some walls torn off well-constructed houses, trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown. (20+ min)
F4: Devastating Damage (207- 260 mph); Well-constructed houses leveled; structure with weak foundations blown off some distance; cars thrown and large missiles generated. (60+ min)
F5: Incredible Damage (261- 318 mph); Strong frame houses lifted off foundations and swept away; automobile sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur. (60+ min)
Tornadoes
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Definition:
A tornado is a rapidly rotating column of air extending from the base of a thunderstorm that comes in contact with the ground.The biggest tornado ever recorded in history:
The biggest tornado ever recorded was the Tri-State Tornado. This devastating column of air took place through parts of Missouri, Illinois, and Indiana on the day of March 18, 1925. It is projected to have been a F5. We can't confirm this though because tornados were not ranked during that period of time. It had a path length of 219 miles(352 km), a duration of about 3.5 hours, and a record speed of 73 mph(117 km/h). It is also recorded to have taken the lives of 650 individuals.
Although tornadoes occur in many parts of the world, they are found most frequently in the United States.....
How do they form?
Before thunderstorms develop, a change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere.
Rising air within the thunderstorm updraft tilts the rotating air from horizontal to vertical.
An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
Anatomy of a Tornado
1. Warm, moist air at the surface rises rapidly, creating an updraft.2. Falling rain evaporates, cooling the air around it.
3. The wall cloud rotates as it's hit with winds from opposite directions.
4. As the rotation intensifies, a visible funnel drops out of the clouds.
5. A prominent overshooting top forms when the updraft is very strong.
6. Powerful updrafts give hail time to form.
7. A dust shroud is kicked up by the tornado's strong winds at ground level.
8. Central downdrafts appear in some tornadoes.
Fujita Tornado Damage Scale
F0: Light Damage (<73 mph); Some damage to chimneys; branches broken off trees; shallow-rooted trees pushed over; sign boards damaged. (1-10 min)
F1: Moderate Damage (73-112 mph); Peels surface off roofs; mobile homes pushed off foundations or overturned; moving autos blown off road. (1-10 min)
F2: Considerable Damage (113-157 mph); Roofs torn off frame houses; mobile homes demolished; boxcars overturned; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground. (20+ min)
F3: Severe Damage (158- 206 mph); Roofs and some walls torn off well-constructed houses, trains overturned; most trees in forest uprooted; heavy cars lifted off ground and thrown. (20+ min)
F4: Devastating Damage (207- 260 mph); Well-constructed houses leveled; structure with weak foundations blown off some distance; cars thrown and large missiles generated. (60+ min)
F5: Incredible Damage (261- 318 mph); Strong frame houses lifted off foundations and swept away; automobile sized missiles fly through the air in excess of 100 meters (109 yds); trees debarked; incredible phenomena will occur. (60+ min)
References
-Anderson, Bruce. Strahler, Alan. (2008) Visualizing Weather and Climate. John Wiley & Sons. Inc. United States of America.
-http://www.youtube.com/watch?v=hJTu4eibeFw
-http://www.nssl.noaa.gov/edu/safety/tornadoguide.html
-http://www.spc.noaa.gov/faq/tornado/
-http://www.nssl.noaa.gov/primer/tornado/tor_basics.html
-http://www.ncdc.noaa.gov/oa/climate/severeweather/tornadoes.html